1. Field of the Invention
This invention relates to an apparatus and method for connecting in fluid tight relation a catheter and a winged inserter body, and more specifically, to an apparatus and method for preventing the transmission of stress between the wings and the place here the catheter is wedged against the body passageway when the wings are folded together during us.
2. Background Description
Winged inserters or catheter adapters of the kind wherein the wings are folded toward one another to hold the needle in the catheter during insertion are disclosed in U.S. Pat. Nos. 4,177,809, 4,194,534 and 4,300,553. In these patents a winged adapter facilitates the handling of catheter and a needle during placement into the lumen of a blood vessel. The wings are folded together to distort the body of the adapter and hold the needle axially in the catheter with the needle tip extended from the catheter in position for penetration into the vessel. The interface between the catheter and the winged adapter body has a bond or weld designed and fabricated so as to be flexible because the body is distorted for holding the needle in the catheter. In particular there is an axial relationship between the tip of the needle and the catheter, commonly known as the lie distance, that must be maintained during insertion of the catheter into a vessel when using the tip of the needle to puncture the vessel and thereafter the shank of the needle to carry the catheter into the vessel.
The interface between the catheter and the body has to be fluid tight to prevent leakage of medication or blood which would present a danger to the patient or the practitioner. Catheters, which are not subject to distortion, are connected to their adapters with a fluid tight connection comprising a collar, wedge, insert, eyelet or funnel shaped member fit within the catheter to expand it into the inside wall of the body of the adapter. That arrangement is only used in a wingless over the needle catheter and rigid adapter wherein there is no expectation of distortion. With a wingless catheter a hub carries the needle in coaxial relationship within the catheter whereby engagement between the adapter and the hub maintains the lie distance during catheter insertion. Consequently, the interface between the catheter and the adapter body is not subjected to flexure or distortion which would cause leakage. U.S. Pat. No. 3,802,433 discloses a tubular insert provided so that the catheter tube is expanded into engagement with the inside wall of the adapter.
The expanded connection between the catheter and the adapter offers a secure mechanical connection which eliminates concern about incomplete welds or bonds which might allow the catheter to slip free of the adapter and enter the patient's blood stream. Even though the advantage of the mechanical connection between the catheter and adapter is preferred and recognized as more reliable it has not been successfully used with a winged catheter where the body of the adapter must be distorted to maintain the needle tip lie distance during the penetrating procedure of insertion. The rigidity of the collar, wedge, insert, eyelet or funnel shaped member resists the intended distortion needed to hold and maintain the axial relationship of the needle and catheter. Without the collar, wedge, insert, eyelet or funnel shaped member, stresses applied, to pinch the needle when the wings are folded, would also distort the interface between the catheter and the adapter. A solution to the problems of reliably holding the catheter with fluid tight juncture while permitting distortion of the winged adapter body to maintain the axial relationship of the needle and catheter has not been found.